MIKE+ Compare

Closes the loop identify -> change -> re-run -> compare. Works on any two .res1d files with the same element ids (same model, different parameters / scenario / rain).

Making the two runs (do this on COPIES, not MIKE+ scenarios)

runs/<case>/00_model_baseline/   <- copy of the model folder, untouched
runs/<case>/00_model_<variant>/  <- second copy; mike_set_values here only
mike_run on each  -> A.res1d (baseline), B.res1d (variant)

Why not mike_set_scenario + create a scenario? Verified on MIKE+ 2026: a scenario created through mikeplus shares its parent's alternatives, so an edit "in the scenario" changes Base too; and if the scenario is given its own alternatives, mikeplus cannot write into them (mike_set_values reports "did not persist"). mike_set_scenario is therefore only for running scenarios that were prepared in the GUI. Copies are unambiguous and audit-friendly.

Tools

• mike_results_compare — {res1d_a, res1d_b, quantity, element?, skip_hours?, top_n?, label_a?, label_b?}
  • ranked mode (no element): peak change for every element of quantity, sorted by |delta| — by_element.top[], n_increased / n_decreased / n_unchanged, n_only_a/b (ids missing on one side). Ask this first: "where did my edit matter?"
  • single mode (element given): comparison{peak_a, peak_b, delta_peak, delta_peak_pct, peak_time_a/b, peak_time_shift_min, mean_a/b, max_abs_diff(+time), rmse, nse_b_vs_a}; for flow quantities (unit m3/s) also volume_a/b, delta_volume(_pct) in m3. aligned = exact (same time base) or interpolated (B was interpolated onto A's steps; say so).
• mike_plot_compare — {res1d_a, res1d_b, quantity?, element, out_png, label_a?, label_b?, rain_dfs0?, skip_hours?} → overlay (baseline dashed grey, variant solid orange), optional inverted hyetograph on top. House style; no title.

Conventions

• Same simulation setup and time window on both sides; pass the same skip_hours (warm-up) to both.
• Report deltas signed, with units and %, plus the peak times: "peak +0.041 m3/s (+5.2 %), 6 min earlier".
• Volume only for flows; for levels use mean / max_abs_diff.
• nse_b_vs_a measures how different B is from A (1 = identical), not model skill.
• If n_only_a/n_only_b > 0, the two runs are not the same network: say so before comparing further.
• Do not claim a figure exists unless the tool returned {ok:true, png}.

Orchestration

mike_results_compare (ranked, quantity=Discharge|WaterLevel)  -> top elements
mike_results_compare (element=<top id>)                       -> deltas for the story
mike_plot_compare    (same element, rain_dfs0 if any)         -> 03_plots/compare_<id>.png
mike_manifest_write  (both res1d as results, the edit as edits)